[Pnp-wg] Full IRV example, was Re: Interim report sections (fwd)
Charlie
oldbogus@ris.net
Mon, 25 Apr 2005 15:01:51 -0600
Having experimented in real-time with various systems, I have become a
Borda/Condorcet supporter. I feel either of these processes can be more
conducive to compromise candidates and positions but IRV purists do not
accept that a candidate with minority support in initial ranking should be
(s)elected.
One of our CO Greens thinks bullet voting should be incorporated into the
systems. It works best by making the voted-for choices of equal value; what
that value might be requires some thought. In fact, in one election some
Greens actually did rank some choices equally; I gave those choices the
average ranking of the two. It works but makes Condorcet complicated to
score. I guess some people don't want as many choices.
Charlie green
Steve Kramer wrote:
> James,
>
> Yes, I did, and I think that you are basically correct. I think the
> other systems mentioned were Condorcet and Borda Count; I would also add
> Approval Voting to the list.
>
> I've had this discussion before with some folks from the Center for
> Voting and Democracy, not entirely to a satisfactory conclusion. The
> fact is, each form of voting has its problems...though some do have more
> than others. However, I do believe without any reservation that Ranked
> Choice Voting is entirely preferable to "bullet voting" in almost every
> case, especially for a single seat; in other words, it's always better
> to rank your choices - "I want Smith first, Jones second, and Brown
> third" - rather than not doing so - "I want Smith". This is just a
> simple case of pushing grassroots democracy; you are giving more weight
> and greater choice to the voter. And Condorecet, Borda, and IRV all
> operate on Ranked Choice.
>
> Steve K.
>
>
> On Sat, 23 Apr 2005, James M Leas wrote:
>
>> Steve Kramer,
>> Did you see the article in Scientific American last year on majority
>> voting methods? IRV was mentioned but not given much space because,
>> according to the article, it did not necessarily provide the outcome
>> desired by a majority of the voters, as your example below illustrates.
>> The article actually focused on another system that it said was better at
>> providing majority rule. I think that system looked at more than just the
>> first place choices, as IRV does.
>>
>> I wonder whether anyone in the Greens has expertise in this important
>> area? Burlington, Vermont voted for a charter amendment to implement IRV
>> in the future mayoral elections. If the state legislature and the
>> governor approve it could happen next year. But if there is a better
>> system we should know about it and consider an amendment for future
>> elections.
>>
>> I would ask, do you only have this problem with IRV if all three have
>> lots of votes? If all three candidates have a similar number of votes
>> maybe dropping the one with the fewest first place is inappropriate and
>> the rankings should all be considered to determine who got the majority.
>> Jimmy
>>
>> On Fri, 15 Apr 2005 01:23:18 -0400 (EDT) Steve Kramer
>> <scooter@guisarme.net> writes:
>>
>>> Folks,
>>>
>>> Here is the full example that I sent to Elizabeth earlier. It shows
>>> how
>>> IRV works, and it also shows that IRV fails the "monotonicity
>>> criterion"
>>> which I mentioned under "Mathematical Truths". (Plurality/FPTP
>>> voting, by
>>> the way, *also* fails it.)
>>>
>>> *Please note* the point I make at the end of this exercise.
>>>
>>> --
>>> Steve Kramer || scooter (at) guisarme dot net
>>> ||
>>> _____________________
>>> ===================================================
>>> | __/^\__ ,-^,|
>>> |/~ \_ { / | "Power concedes nothing without a
>>> demand.
>>> \/\ |! | It never has, and it never
>>> will."
>>> / / ) |___
>>> (_ \ \ / Frederick Douglass
>>> ~v^ ?_,-'
>>>
>>> ---------- Forwarded message ----------
>>> Date: Sun, 10 Apr 2005 04:51:12 -0400 (EDT)
>>> From: Steve Kramer <scooter@guisarme.net>
>>> To: Elizabeth Arnone <elizarnone@comcast.net>
>>> Subject: Re: Interim report sections
>>>
>>> On Fri, 8 Apr 2005, Elizabeth Arnone wrote:
>>>
>>>> However, I don't understand #3 - which says, "no winning
>>>
>>> candidate should
>>>
>>>> ever lose as a result of being ranked *higher* by any voter. How
>>>
>>> would this
>>>
>>>> happen? Same for #4.
>>>>
>>> Here's the example. Let's say you hold an IRV election with three
>>> candidates,
>>> and the following votes are counted:
>>>
>>> First Second Third
>>> 38 voters voted... Smith Allen Johnson
>>> 25 voters voted... Johnson Allen Smith
>>> 15 voters voted... Allen Smith Johnson
>>> 15 voters voted... Allen Johnson Smith
>>> 7 voters voted... Smith Johnson Allen
>>>
>>> Here's how we count this in IRV:
>>>
>>> Smith has 45 first-place votes, Allen has 30, and Johnson has 25. So
>>> Johnson
>>> is eliminated. *All* voters who listed Johnson first listed Allen
>>> second, so
>>> every one transfers over to Allen. Smith now has 45 votes, and
>>> Allen has 55
>>> votes (30, plus the 25 that were transferred over).
>>>
>>> Allen wins.
>>>
>>> Now let's consider if the votes had been slightly different.
>>>
>>> First Second Third
>>> 38 voters voted... Smith Allen Johnson
>>> 25 voters voted... Johnson Allen Smith
>>> 15 voters voted... Allen Smith Johnson
>>> 15 voters voted... Allen Johnson Smith
>>> 7 voters voted... Johnson Smith Allen
>>>
>>> Look very carefully. The **only** thing that changed is that the
>>> seven voters
>>> at the bottom of the table decided to list Johnson first, *ahead* of
>>> Smith. In
>>> other words, these seven voters bumped Smith down a bit by not
>>> listing him
>>> first. This should not help Smith in any way.
>>>
>>> But here's how it ends up happening in IRV: Smith has 38
>>> first-place votes,
>>> Allen has 30, and Johnson now has 32. So it's Allen who is
>>> eliminated, and his
>>> votes are redistributed. As it turns out, 15 of Allen's 30 go to
>>> Smith, and 15
>>> go to Johnson as second-place choices. Smith now has 53 votes (38,
>>> plus the 15
>>> he got being second to Allen), and Johnson has 47 votes (32, plus
>>> the 15 he got
>>> being second to Allen).
>>>
>>> Smith wins.
>>>
>>> So...when seven voters list Smith ahead of Johnson, Allen wins. But
>>> when those
>>> same seven voters switch, and list Johnson ahead of Smith - and
>>> nobody else
>>> changes a single thing! - then suddenly *Smith* wins.
>>>
>>> This doesn't *precisely* prove what I wrote above...but it does show
>>> that under
>>> IRV, a candidate can get a lower "score" and end up winning an
>>> election he
>>> otherwise would have lost with the *higher* score.
>>>
>>> And again, whatever method you choose, you'll end up with something
>>> weird like
>>> this. That's the point of that section.
>>>
>>> --
>>> Steve Kramer || scooter (at) guisarme dot net
>>> ||
>>> _____________________
>>> ===================================================
>>> | __/^\__ ,-^,|
>>> |/~ \_ { / | "Never was anything achieved without
>>> danger."
>>> \/\ |! |
>>> / / ) |___ Niccolo Machiavelli
>>> (_ \ \ /
>>> ~v^ ?_,-'
>>> _______________________________________________
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>>>
>>>
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